At 42, Paul Ryan is the first national candidate clearly on the GenX side of the generational line, closer in age to teen Olympic gymnast Gabby Douglas than he is to 69-year-old Joe Biden, the man Ryan wants to replace as vice president.

Republican candidate Mitt Romney's choice of the Wisconsin congressman as his running mate complicates for both parties a cross-generational argument that has largely been swinging between 20-something Millennials and seniors older than 65.

Read more at USA Today.